Can I directly upgrade my jailbreak?

[azndude1]

Currently I'm jailbroken to 4.0.1, Can I jailbreak it to the latest iOS without unjailbreaking it?

If so, how would i do that? Sorry I haven't played around with jailbreaking in a while...

[dotFIVE]

The latest version, 4.1., can be jailbroken. You won't be able to upgrade without starting fresh though; just restore from a backup afterward to bring back your texts, SMS messages, etc.

If you don't rely on an unlock for an unofficial carrier, simply update to 4.1 and then jailbreak with either greenpois0n or limera1n.

If you do rely on an unlock, you'll need to use custom firmware from PwnageTool (if you are on Windows, use the latest redsn0w and then point it to the custom 4.1 firmware).

[iYeow]

Everytime you do an upgrade or restore, your jailbroken device will be unjailbroken.
The rest of your questions have been answered by dotFIVE

[azndude1]

ok thanks...when i restore, what exactly will i lose?

[iYeow]

It will be like a brand new iphone. You can always sync back contacts, pictures, videos, songs and so forth. Only jailkbreak apps will be gone and you will have to reinstall again.